Optimization of surface-mount permanent magnet synchronous machines for low duty-cycle, high-torque applications

Abstract

A motor is designed and tested for the MIT Robotic Cheetah project. The robot presents unique motor design challenges as it contains eight separate motors with different drive cycles, each consisting of short duration large torque commands followed by periods of lesser torque requirement. The ratio between maximum torque and rated torque is approximately 10:1. A design was selected through use of a brute-force grid sweep that makes use of a fast-running hybrid modeling technique. This design was then built and tested, resulting in a machine that weighs 810 g and produces 30 Nm of torque, or 60% of the mass and 300% of the torque of a commercially-available machine with the same outer diameter.